| Presentation styles / Using presentation styles | |
A desktop application should follow the current desktop settings. The front-end tries to determine the default font for the desktop, and also offers a global font chooser to let the end-user define which font best matches his expectations.
In most cases it is not possible to know what a potential end-user might expect regarding the font family. Therefore, your application should avoid the usage of explicit font families and use only the fontWeight/fontStyle/fontSize properties. A specific font family should be used only if the client can't determine a proper default font family for the desired platform.
Use abstract font sizes such as medium, large, small, or sizes relative to the user-chosen font (using em units), rather than absolute point values. In an HTML browser you can choose two fonts (proportional/fixed), and a well-designed document should not use more than 2 fonts. This is also valid for applications.